Multi-layer cache stack technologies have been used in storage technologies. In the multi-layer cache stack technologies, a solid-state storage devices, i.e., solid storage disks (SSDs), are used. During applying procedure of the multi-layer cache stack technologies, operations of flushing pages from the solid-state storage device to a hard disk are needed sometimes. However, in the prior art, there are problems such as low throughput of flushing process when performing operations of flushing pages from the solid-state storage device to the hard disk, thereby affecting the efficiency of applying the multi-layer cache stack technologies, and possibly bringing poor user experience to users.